How Diverticular Disease Is Diagnosed

Diverticular Disease Might Not Always Require a Diagnosis

In most cases, diverticular disease has no symptoms. When diverticular disease there are no symptoms, there is no reason to go looking for it or to treat it. However, it might be discovered as what physicians will refer to as an “incidental” finding on a screening colonoscopy.

Diverticula are more common in people over the age of 40 years. Starting at the age of 50 years, it’s recommended that people who are at average risk for developing colon and rectal cancer have a screening colonoscopy.  That colonoscopy is done to look for polyps, which are the precursor to colon cancer. Any polyps that are found during a colonoscopy are removed, which effectively prevents them from progressing to becoming cancerous cells.

During such a screening colonoscopy, the physician completing the test will also be on the lookout for any other potential findings within the colon. In some cases, that might mean discovering diverticula that aren’t currently causing any symptoms.

If there are symptoms that are suspected to be from diverticula that are inflamed and causing a condition called diverticulitis, one or more tests might be done to confirm it. Tests that might be done to diagnose diverticular disease are a colonoscopy or an abdominal computed tomography (CT) scan.


A colonoscopy is a test that is done to look inside the large intestine. The colon is where water is absorbed and food that hasn’t been broken down fully is processed further. After making its way to the end of the colon, the stool is stored in the rectum, where it eventually leaves through the anal canal and sphincter as a bowel movement.

Preparing for the Test

During a colonoscopy, a colonoscope, which is a long tube with a light and a camera on the end, is inserted up through the anus. In order to complete this test, and have it be as comfortable as possible for patients, some steps are taken in the days prior.

It’s important for the colon to be clear of any stool so that the physician completing the test can have an unobstructed look at the wall of the colon. This is called a colonoscopy preparation, or prep, and is usually considered the more challenging part of the entire procedure.

The physician who is completing the colonoscopy will prescribe a preparation procedure based on the preference in their practice and taking any considerations about the patient (such as other health conditions or any preferences) into account.

Preparations are usually done by using strong laxatives that may be given in liquid or pill form, and sometimes in combination. In some instances, an enema might also be used. Fasting before the test is also necessary, so a diet of clear liquids is prescribed usually the afternoon before the test and nothing to eat or drink after midnight the night before the test.

An IV will be started prior to the colonoscopy, in order to give fluids and sedating medications. After the sedatives are given, the physician will complete the test. When the test is over, the sedatives will be stopped and patients will wake up and be monitored for a short time. It’s not safe to drive because of the sedatives, so a friend or family member will need to drive home. After resting and taking it easy for the rest of the day, most people can return to their regular schedule the next day.

Obtaining Results

For some patients, a follow-up appointment with a physician or other healthcare professional to talk about the results of the test may be needed. In some cases, polyps might be removed or biopsies might be taken during the colonoscopy.

There will be tests done on those tissues and the doctor will receive the results. If any diverticula were found, that will also be discussed, as well as if that has any impact on diet or lifestyle.

Abdominal CT Scan

Diverticular disease may also be diagnosed through a CT scan. This test is a type of x-ray that is specialized in order to see the organs and structures inside the abdomen. This test might be used to diagnose diverticular disease, especially if there are currently intestinal symptoms (such as pain or bleeding) and a colonoscopy isn’t possible.

A CT scan is a painless and non-invasive test. The output is an electronic image which can be easily viewed and transported. The only preparation is fasting for a few hours prior to the test.

What to Expect

You will be asked to remove any metal jewelry or other metal items such as eyeglasses. The CT machine is large, with a table that slides into the machine. You will lie on the table and when the test begins, the table will move into the machine until you are in the correct position. The machine will use an x-ray to take images. The technician conducting the test will give any instructions because it’s important to remain still and hold the breath at certain points. The test will usually take about 30 minutes, depending on how many images are needed.

Contrast dye is used so that some body structures show up better on the final images. For an image of the colon, the dye will be given both as a drink and in an IV. The drink will be given prior to the start of the test.

Obtaining Results

After the CT scan, any necessary follow-up will be individualized based on the results of the test and the health of the patient. In some cases, the test is being done not only for the possibility of diverticulitis but also to assess the possibility of other conditions that may be causing the symptoms. When diverticulitis is diagnosed, a treatment plan will be needed right away because of the acute nature of this condition. If there are diverticula found in the colon but they’re causing no symptoms, there may or may not be a need to make changes to diet and lifestyle.

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Article Sources
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Additional Reading
  • American Society of Colon and Rectal Surgeons. "Diverticular Disease." 2018.
  • Harvard Men's Health Watch. "Diverticular disease of the colon.” Harvard Health Publishing. 5 Dec 2015.  
  • Tursi A, Papa A, Danese S. "Review article: the pathophysiology and medical management of diverticulosis and diverticular disease of the colon.&rdquo Aliment Pharmacol Ther. 2015;42:664-684. doi: 10.1111/apt.13322.